Site developers can preview a website before a domain/DNS has propagated to a new location on a server in Web Hosting.
In most cases the Web Hosting Service will establish a preview URL to assist during site migrations from one server to another. See Web Hosting - Site Migrations to New Servers.
You can also preview your site via the Plesk Administrative Control Panel using the Site Preview feature pictured here:
Note: Another option for previewing your site when moving to a new server IP is to add the records for the domain to the "hosts" file in your local operating system.